Dresden 2009 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 46: Correlated Electrons: Quantum Impurities, Kondo Physics
TT 46.2: Talk
Friday, March 27, 2009, 10:30–10:45, HSZ 301
Superperturbation solver for quantum impurity models — •Sergey Brener1, Alexander Lichtenstein1, Hartmut Hafermann1, Christoph Jung1, Kelly Patton1, Mikhail Katsnelson2, and Alexei Rubtsov3 — 1I. Institut für Theoretische Physik, Universität Hamburg, Deutschland — 2Institute for molecules and materials, Radboud University of Nijmengen, The Netherlands — 3Department of physics, Moscow State University, Russia
We present a very efficient solver for a general Anderson impurity model. It is based on a perturbation around a solution obtained from exact diagonalization using a small number of bath sites. Satisfactory agreement is found for a single bath site over a wide range of parameters. The method proves superior to QMC for a calculation of spectral properties for real energies by analytical continuation due to the absence of statistical noise. It can also be applied to calculating of two-particle correlators, which allows to investigate, for example, transport properties of nano-systems or spin correlations which are essential for description of a Kondo cloud.